Examples of current and recent research projects
Long-term dynamics of wading bird populations as indicators of ecological change.
Using a combination of extensive and intensive monitoriong techniques, myself and my research team have systematically monitored nesting by wading birds during the past 20 years in the 3,300 km2 of the Everglades. This work has included studies of reproductive success, energetics, nutrient cycling, foraging ecology, and contamination. When combined with a rich historical record of nesting, the resulting database provides a rare glimpse at how wading bird populations have changed in size, location, timing and success as a result of anthropogenic change in the hydrology of the Everglades. The results have helped understand the historical hydrological functioning of the ecosystem, and have been used to design and modify plans for restoring the Everglades ecosystem. (John Simon, Peter Frederick)
- Severe droughts are linked with exceptionally large nesting events
- How wading bird populations can be used as an indicator of restoration success
- Monitoring bird populations over large areas
- Use of the superpopulation approach to estimate colony size over time
Consequences of methylmercury contamination on wading bird reproduction and survival.
By the early 1990s, most high trophic status vertebrates in the Everglades showed very high levels of contamination with methylmercury. We have used both natural and manipulative exposure experiments to examine the effects of methylmercury on avian reproduction. Taken together, the results indicate that even very low, chronic exposure to methymercury can have important sublethal effects on appetite, immune function, reproduction, and survival. Our most recent experimental work suggests strongly that low, environmentally relevant MeHg exposure can affect endocrine function to the extent that male-male pairings are significantly increased. The net result of these effects can be a regional demographic sink for the birds. (Evan Adams, Nilmini Jayasena, Peter Frederick)
- Effects of MeHg on egret physiology and immune function
- 100-year history of avian mercury contamination using museum specimens
- Exposure levels for fish eating birds in south Florida
- The Everglades mercury story and management for other wetlands
- MeHg-mediated endocrine disruption in ibises
- MeHg exposure linked to population decline in ibises
- Mate choice and MeHg exposure
Demography and movements of endangered Wood Storks (Mycteria americana).
We have used satellite telemetry intensively and extensively to understand regional and seasonal movements, habitat use, and survival of Wood Storks. This species moves widely in response to hydrologic change and food availability in the southeastern US. Working with a consortium of biologists throughout the range, we have gathered enough rangewide survival and reproductive success information to construct the first demographic models for this species. (Rena Borkhataria, Becky Hylton)
- Demographic model for the Wood Stork
- Nestling health and postfledging survival of Wood Storks
- Identifying landscape features associated with colony longevity
Stork colony longevity as an indicator of habitat quality.
Wood Storks are important wetland indicators and are listed as Endangered in the southeastern United States, however, the information available for identifying and prioritizing stork colony and feeding habitat are limited and dated. We aim to compare attributes of Wood Stork habitat colonies (e.g., vegetation, physiographic, land use and hydrologic characteristics) that lasted many years, with those that winked out after only a few years, as a way to identify high priority colony characteristics in a survival analysis framework. Using a 39-year record of colonies, our goal is to make the resulting information and tools directly usable by permitting, conservation and land planning agencies, and NGOs. (Ross Tsai, Peter Frederick). Please see http://www.wec.ufl.edu/faculty/frederickp/woodstork/ for my information.
Effects of fire on nutrient flow and aquatic community organization.
Fire is an historic component of the Everglades, of natural and anthropogenic origin. Typically, fire occurs at the start of the rainy season, May, however recent fire management in many parts of the Everglades includes prescribed fire during December-April, the dry season. Numerous fire managers have reported concentrations of wading birds present in prescribed burn areas immediately after fires and sometimes for weeks afterwards. While it is known that fires release nutrients, it is unclear that nutrients are the mechanism by which wading birds are attracted to burned areas. This research is to determine whether trophic effects occur via nutrients, light, or simple vegetative clearing. (Louise Venne)
Interactions of alligators and long-legged wading birds in breeding colonies.
Animals often use cues provided by other animals about habitat quality – and may even have symbiotic relationships with those indicator animals. There are numerous anecdotal observations of wading birds nesting preferentially above alligators in colonies. However, it is not clear that the relationship is nonrandom, and if so, why it occurs. In addition to determining if nesting wading birds are attracted to alligators based on visual cues, we are attempting to quantify the potential costs and benefits of the relationship for gators (food, fertilized fish ponds) and birds (protection from predators, high fish densities). (Brittany Burtner)
Use of unmanned aerial vehicles (drones) to monitor nesting of large populations of birds.
Aerial surveys by humans are prone to a number of biases, and are both costly and dangerous. In addition, it may be important to pinpoint the locations of nests in order to estimate colony size over the entire season. In collaboration with researchers in the Florida Cooperative Research Unit, Department of Mechanical and Aerospace Engineering, and the Geomatics Section of the School of Forest Resources and Conservation, we have developed a series of small, autonomous, hand launched aircraft capable of taking fully georeferenced high resolution digital images along pre-programmed flight paths. See http://uav.ifas.ufl.edu/ (John Simon, Peter Frederick)
Conservation of the critically endangered White-bellied heron in Bhutan.
The White-bellied heron (Ardea insignis) is the second largest heron in the world, and is globally highly imperiled, with perhaps 200 individuals existing. Very little is known about this secretive and sparsely distributed species. This work has been aimed at understanding current distribution, abundance and ecological relationships. This work has been spearheaded by biologists with the Royal Society for the Protection of Nature, Bhutan, and Peter has participated for three years as part of a team effort studying energetics, foraging ecology, habitat use, and reproductive ecology. (Peter Frederick)